(Corbett, OR)  --  An elderly driver is seriously injured after his vehicle tumbled 60-feet down an embankment near the Vista House in the Columbia River Gorge yesterday.  Multnomah County Sheriff's deputies say the driver mistook the "reverse" gear for "park," went over the embankment, and fell onto the Historic Columbia River Highway below.  The man is being treated at an area hospital for serious, but non-life-threatening injuries.